19" COLOR MONITOR

c8 SAlUlSUNG SERVICE MANU- AL

19" COLOR MONITOR

MODEL: CC95"t1

CONTENTS

IMPORTANT SERVICE SAFETY PRECAUTIONS ... 3

ENGINEERING SPECIFICATIONS ... 5

THEORY OF OPERATION 1. Line input ... 10

2. Power supply ... 10

3. Horizontal ... 11

4. Vertical deflection ... 15

5. Sync. processing ... 16

6. Video ... 17

7. Tube biasing ... 18

DISASSEMBLY INSTRUCTIONS ... 19

BLOCK DIAGRAM ... 21

ADJUSTMENTS ON INSTALLATION How to adjust ... 23

ALIGNMENT INSTRUCTIONS 1. B

+

Adjustment ... 28

2. Horizontal frequency adjustment ... 28

3. Horizontal Phase Adjustment ... 28

4. Vertical frequency adjustment ... 28

5. Focus adjustment ...•. · ... 28

6. Side pincushion adjustment ... 28

7. Horizontal linearity adjustment ... 28

8. Vertical linearity adjustment ... 28

9. Horizontal centering adjustment ... 28

10. Vertical centering adjustment ...•... 28

11. Width adjustment ... 28

12. Vertical size adjustment ... 28

13. Color purity adjustment ... 29

15. White balance adjustment ... 30

16. Static (center) convergence ... 30

17. Dynamic convergence ... : ... 31

TROUBLE SHOOTING GUIDE ... 32

WIRING DIAGRAM AND PARTS LOCATION ... 37

PRINTED CIRCUIT BOARDS 1. Power PCB ( TOP view) ... 39

Power PCB ( BOTTOM view) ... 40

2. Deflection PCB (TOP view) ... .41

Deflection PCB ( BOTTOM view) ... .42

3. Video PCB ( TOP view) ... 43

Video PCB (BOTTOM view) ... .44

4. CRT PCB( TOP and BOTTOM view) ... .45

5. HN Regulation Module PCB ( TOP and BOTTOM view) ... 46

6. Output TR PCB ( TOP and BOTTOM view) ... 46

7. Stand PCB (TOP and BOTTOM view) ... .47

8. LED PCB ( TOP and BOTTOM view) ... 47

9. FBT PCB (TOP and BOTTOM view) ... 48

CABINET EXPLODED VIEW / PARTS LIST 1. Cabinet exploded view ... 49

2. Cabinet parts list ... 51

3. ·Electrical parts list ... 54

SCHEMATIC DIAGRAM ... 75

WAVEFORMS· ... 84

SEMICONDUCTOR LEADS IDENTIFICATION ... 86

2

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only by qualified service technicians who are thoroughly familiar with all of the following safety checks and servicing guidelines.

WARNING

1. For continued safety, do not attempt to modify the circuit.

2. Disconnect the AC power before servicing.

3. Semiconductor heat sinks are potential shock hazards when the chassis is operating.

SERVICING THE HIGH VOLTAGE SYSTEM AND PICTURE TUBE

When servicing the· high voltage system, remove the static charge by connecting a 20kohm resistor in series with an insulated wire( such as a test probe) between the chassis and the anode lead. (The AC line cord should be disconnected from the AC out- let.)

1 . The picture tube in this display monitor employs integral implosion protection.

2. Replace with a tube of the same type and num- ber for continued safety.

3. Do not lift the picture tube by the neck.

4. Handle the picture tube only when wearing shat- ter proof goggles and after discharging the high voltage anode completely.

X-RADIATION AND HIGH VOLTAGE LIMITS

1. Be sure all service personnel are aware of the procedures and instructions covering X-radiation.

The only potential source of X-ray in a current solid state display monitor is the tube. How- ever ,the picture tube does not emit measurable X-ray radiation if the high voltage is as specified

It is only when high voltage is excessive that X- radiation is capable of penetrating the shell of the picture tube,including the lead in glass material. The important precaution is to keep the high voltage below the maximum level specified.

2. It is essential that serviceman have available at all times an accurate high voltage meter. The calibration of this meter should be checked pe- riodically.

3. High voltage should always be kept at the rated value - no higher. Operation at high voltages may cause a failure of the picture tube or high voltage circuitry and,also under certain conditions,may produce radiation in excess of desirable levels.

4. When the high voltage regulator is operating properly there is no possibility of an X-radiation problem.

Every time a color chassis is serviced,the bright- ness should⁴be tested while monitoring the high voltage with a meter to be certain that the high voltage does not exceed the specified value and that it is regulating correctly.

5. Do not use a picture tube other than that specified or make unrecommended circuit modifications to the high voltage circuitry.

6. When troubleshooting and taking test measure- ments on a display monitor with excessively high voltage, avoid being unnecessarily close to the display monitor. Do not operate the display monitor longer than is necessary to locate the cause of excessive voltage.

BEFORE RETURNING THE DISPLAY MONITOR

Fire and Shock Hazard

Before returning the display monitor to the user,per- form the following safety checks:

1. Inspect all lead dress to make certain that the leads are not pinched or that hardware is not lodged between the chassis and other metal parts in the display monitor.

2. Inspect all protective devices such as nonmetallic control knobs, insulating materials, cabinet backs, adjustment and compartment covers or shields,isolation resistor-capacitor net- works,mechanical insulators,etc.

3. To be sure that. no shock hazard exists, check for leakage current in the following manner:

• Plug the AC line cord directly into a 12Ovolt AC outlet. (Do not use an isolation transformer for this test)

• Using two clip leads,connect 1.5 kohm,lO watt resistor paralleled by a 1.5uF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as electrical conduit or electrical ground connected t~ earth ground.

• Use a SSVM or YOM with 1000 ohms per-volt or higher sensitivity to measure the AC voltage drop across the resistor.(See Figure 1.)

• Connect the resistor to all exposed metal parts having a return path to the chassis (metal cabinet, screw heads, knobs and shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor.

• Any reading of O.3volt RMS (this corresponds to O.5milliamp.AC) or more is excessive and indicates a potential shock hazard which must be corrected before returning the display monitor to the user.

SAFElY NOTICE

Many electrical and mechanical parts in this chassis have special characteristics often pass unnoticed and the protection afforded by them can not necessarily be obtained by using replacement components rated for higher voltage,wattage,etc.

Replacement parts that have these special safety char- acteristics are identified in this manual,and its supple- ment electrical components having such features are

4

AC VOLll£TER

1500 0

TO

EXPOSED

~AL PARTS

TO KNOWEN

EARTH GROlN) Figure 1. Leakage Current Test Circuit

identified by a& in the Parts List and Schematic diagrams.

Before replacing any of these components,read the Parts List in this manual carefully. The use of sub- stitute replacement parts that do not have the same safety characteristics as specified in the Parts List may create shock, fire, or other hazards.

ENGINEERING

1. DESCRIYrION

This specification describes in detail, the electri- cal and mechanical performance of a 20-inch color monitor. This monitor is designed to work with the CAD/CAM workstation or PC (personal computer).

The monitor will accept RGB analog video output of the computer and display this information in up to infinite color renditions. Monitor syncronization is controlled by a sync on green video or any polarity separate TTL sync or composite TTL sync. All parameters shall be met within the limits specified in this document unless otherwise specified. The specification is subject to change without notice.

2. MECHANICAL DESCRIPTION 2.1 Dimension

525(L) x 484(W) x 488(H) mm : Net 622(L) x 558(W) x 559(H) mm : Gross 2.2 Weight

35 Kg 37 Kg

Net Gross

3. POWER INPUT SPECIFICATIONS 3.1 Input Voltage

120V range : AC 90 - 132 volts.

220V range : AC 198 - 264 volts.

3.2 Input Frequency 50 ±3 Hz or 60 ±3 Hz 4. SIGNAL INPUT SPECIFICATIONS

4.1 Signal Wave Form

Signal input is based upon EIA standard RS343.

4.2 Video Signal

a)Type R(Red),G( Green),B(Blue) analogtype

(Composite SYNC signal will be taken from the Green video signal.)

b) Level

Composite Non-composite c) Signal polarity d) Impedance

: 1.0 Vp_p Norminal : 0.7 Vp_p Norminal

Positive bright

SPECI FICATIONS

Terminated 75 ohms 2%

Unterminated: Greater than 10 Kohms switch selectable.

4.3 Sync Signal a) Type

Composite sync on Green or composite H/V sync or seperate H/V sync are automatically selectable.

b) Level

Composite : SYNC to total signal ratio

= 28.6 5%

External : DC coupled TTL level

( separate H/V sync and composite H/V sync.) c) Signal polarity: Positive or negative.

4.4 Sync Frequency a) Horizontal :

46-52KHz (50 KHz version) 52-58KHz

58-64KHz (64 KHz version)

b) Vertical 55-65Hz non-interlaced 4.5 Input Connector

BNC type receptacle for each RG.B video signals and external SYNC signals.

4.6 Signal Timing : see timing chart (page 9) 5. CRT SPECIFICATIONS

Parts NO Type Mask Pitch Phosphor Transmission Face

E8111 B22 ET AR or M48JLK22X

20" 90 DEGREES, 29MMO, SELF-CONVERGENCE

0.31mm

RG.B, Medium Short Persistance

Approx.70%

AR Panel 6. RESOLUTION

1280 dots x 1024 lines ( 64 KHz version ) 1024 dots x 768 lines ( 50 KHz version ) 7. ENVIRONMENT

7.1 Operating Environment

a) Temp 0 - 4QoC

b) Humidity c) Altitude

10. - 90%

3000m max.

7.2 Storage and Shipment Environment a) Temp -30 -

+

6SoC b) Humidity 10 - 90%

c) Altitude 12,000m max.

7.3 Vibration (Package Condition) a) Frequency TBD

b) Vertical TBD

c) Horizontal TBD 7.4 Shock

1 corner, 3 edges and 6 surfaces 8. ELECTRICAL PERFORMANCE

8.1 Testing Conditions

All tests must be perfomed under "Standard Testing Condition " except where otherwise noted.

" Standard Testing Condition " is defined as:

a) AC Supply Voltage 120VAC, 60Hz b) Ambient Temperature 20. SoC

c) Brightness Control Center Click d) Contrast Control Set to maximum

video gain e) View Direction

Parallel to the CRT axis

The set shall be tested with facing to North-east.

f)Magnetic Field: 0.03m telsa steady state in any orientation.

g) Thermal Stablization

After 20 minutes from the time AC power has been applied.

8.2 Power Supply

Input Current : 2.5A max.

Power Consumption 8.3 Video Output

8.3.1 Band Width

(120VAC / 60Hz) 140W max.

SOHz to 100MHz ( 3DB ) - 64KHz version SOHz to 70MHz ( 3DB ) - SOKHz version

*

Amplifier response shall be less than 3dB down at 100MHz (70MHz) as referenced to SOHz and with 20 volts of drive to the CRT.

6

8.3.2 Rise / Fall time

S.Onsec max. - 64KHz version 6.0nsec max. - SOKHz version 8.3.3 Video Amplifier Differential Gain Less than S% for 30 volts p_p of video at the CRT.

8.3.4 Black Level Stability

Black level shift to be less than 1 % of peak luminance from 10% to 90% average picture

level.

8.3.5 Contrast Control Range

Shall provide a minimum of 7dB of adjustment range from minimum to maximum setting.

8.4 Image

8.4.1 Image Size

Horizontal : 360 ± Smm Vertical : 270 ± Smm 8.4.2 Image Centering Edge of bezel opening

A

G Display area

IA-BI

s

4mm IC-DI ^S 3mm 8.4.3 Geometry

D

Trapezoid / Parallelogram EF - GH

- - - x 100

s

1 % max.

EF + GH (horizontal) EG - FH

- - - x 100

s

1 % max.

EG

+

FH (vertical) F

B

H

Pincushion /

Horizontal:S 4 mm max. (A,B) Vertical :S 3.4 mm max. (C,D) Rotation : 1.0% max

8.4.4 Linearity

The linearity will be measured by means of full screen cross hatch pattern.

The pattern to be white lines on a black background.

Linearity to be calculated as follows MAX - MIN

x 100 :s 5 % max.

MAX + MIN MAX

MIN

Maximum square size.

Minimum square size.

8.5 Overall Performance 8.5.1 Mis-convergence

Convergence shall not deviate more than O.3mm in a central area bound by a circle.

The diameter of this circle is 260mm.

Elsewhere, deviation shall not exceed O.5mm.

360mm

1 ___ '

^---~'I-

270mm

B

Center area of display (A) : O.3mm max.

Peripheral area of display (B) : O.5mm max.

8.5.2 Luminance

a) Maximum Luminance :

No less than 30 foot lambert.

b) Uniformity

No less than 60% of peak luminance.

8.5.3 White Coordinate

The reference white shall be that of the black body at temperature of 9,300 degrees K. C.I.E.

coordinates are X = 0.281, Y = 0.311.

Coordinate to be whitin .03 when measured at 5 foot lambert light output settings.

Coordinate to be whitin .02 when measured at 20 foot lambert light output settings.

At 20Ff-L Luminance: X=0.281 ± 0.02 Y = 0.311 ± 0.02 At 5 Ff-L Luminance: X=0.281 ± 0.03 Y = 0.311 ± 0.03 8.5.4 Purity

Conspicuous miss-landing shall not be visible within display area at distance of 60 cm from CRT surface at 15 foot lambert white luminance.

8.5.5 Jitter

Less than 1 dot, or invisible at distance of 60 cm from CRT surface.

8.5.6 Dispaly regulation Due to brightness variation :

Within 1% of display size.

Due to power supply variation :

Within 1% of display size.

Due to temperature variation :

Within 2% of display size.

9. AUTOMATIC DEGAUSSING

Automatic degaussing of the CRT to be provided at switch on.

10. APPLICABLE DOCUMENTS

UL 478 : Standard for safety. information- processing and business equipment.

CSA C22.2 :Data processing equipment.

FCC R ULES PART Class A computing devices IS SUBPART J

DHHS RULE 21 X-ray emissions.

SUBCHAPTER J

VDE 0806 : Safety Specification for business machine

VDE0871 Regulation for the radio frequency interference suppressions of high frequency apparatus and installations, class A computing equipment ref.

0871/6.78

PTB : German X-ray decree of march, 1973 IEC380 : Safety of office appliances.

IEC435 : Safety of data processing equipment.

BS5850 : Britith standards institute standard for office machines.

11. Applicable Signal Timing Chart.

8

Video input signal timing chart (Standard timing)

(1) HN COMPOSITE SYNC.

R.G.B signal (analog)

VIDEO (R.G.B)

_

____

H-SYNC.

"-

(HORIZONTAL) 12.075 DISPLAY TIME

~

-

V-SYNC.

(VERTICAL) 1024H DISPLAY TIME

0,415

I_I

^1.774

_{-N 1.1}

_2Q!I

1.434 3H

15.698 --~ (unit :uS) 1---1060H -~

(2) SYNc. ON GREEN Green signal

(HORIZONTAL)

I I+---

^{12.075 .}

I I

UI

DISPLAY TIME

L.J

0,415 .

I_I

^1.774

1.434

+ - - - - - 15.698 ---+1 (unit: uS)

(VERTICAL)

~.

1024HH---+·

I I

DISPLAY TIME ~

~U

^30H

+ - - - - 1060H - - - - I (unit: H)

(unit :H)

THEORY

1. LINE INPUT

The input rectifier section converts the AC line voltage into a crudely filtered and unregulated DC voltage, powering the switching regulator. The input section is a full-wave bridge.

1.1. FILTER

To reduce noise from the power supply, a low-pass filter isolates the switcher. The conducted noise is filtered by X and Y capacitors and a common mode transformer.

2. POWER SUPPLY

The design uses a discontinuous flyback topology operating in current-mode resulting in a multiple output switcher with outputs which track well. There are no output filter chokes. Slower diodes are used.

The fast transient response of the control loop maintains picture integrity. Very fast current limiting protects the switcher against short circuits.

2.1. P.W.M. INTEGRATED CIRCUIT

The 3842 is an integrated current mode pulse width modulator. It consists of an oscillator, error amplifier, current sense comparator, under-voltage lockout, and an output MOSFET driver stage.

2.2. UNDER-VOLTAGE LOCKOUT

This circuit insures that V cc is adequate to make the 3842 fully operational before enabling the oscillator, voltage reference, and before turning on the output stage. The turn-on/off thresholds are at l6v and lOv respectively.

2.3. OSCILLATOR

The oscillator consists of a pull up resistor from the Sv reference to pin 4 of IC601 and a timing capacitor to ground. When the voltage ramps up to about 2.8v

OF

10

OPERATION

on pin 4 of IC601 an internal current source pulls down, discharging the timing capacitor to a l.Ov level.

This level releases the current source and starts the next cycle. Oscillator frequency is roughly equal to l/.5SRC.

Synchronization is achieved by feeding timing pulses from a reference into the oscillator.

2.4. OUTPUT STAGE

The 3842 has a single totem-pole output capable of operating to l.0 A peaks and a 200mA average cur rent.

2.5. CURRENT SENSE COMPARATOR

Current-mode controllers inherently keep close watch over the pass transistor's current. Pin 3 of IC601 is connected to a voltage comparator which shuts off the output when current reaches the desired level, as prescribed by the error amplifier. This way the controller will only allow the needed amount of power into the output transformer. This method differs from most pulse width controllers which compare the error amplifier's output against the oscillator's voltage ramp. This results in control of on-time, which does not necessarily mirror the power stored in the transformer.

This comparator also serves the dual purpose of monitoring current limit. Any time pin 3 of IC601 rises above 1 volt the output will terminate.

Output -short circuits and core saturations are detected before they destroy the pass transistor.

2.6. ERROR AMPLIFIER

Voltage on pin 2 of IC601 is compared with a 2.Sv, 2% source. Errors in output voltage are amplified and fed to pin 1 of IC601 where they are frequency compensated by an RC back to pin 2 of IC60l. This error voltage is dropped by l.4v and divided by 3 before being fed to the current comparator.

In this application, the error amplifier is on the secondary side of the switcher. Inside the

IC604(TlA31), T603 in the data book, is a programmable reference. In side it consists of a temperature compensated reference and an amplifier.

Any error in output voltage is compared against 2.5 volts and amplified. Frequency compensation is handled by C610. Error current passes through an optocoupler to another error amplifier.

2.7. Vee

The 3842 draws very little current in start up mode.

There is enough power from the line bleeder R604 to slowly charge C616 to the 16 volts needed to start the switcher. When switching begins the V cc falls quickly but before it drops to the 10 volt turn off level, the horizontal section of the monitor should be up and running. A few turns of wire from around the flyback transformer supplies power and synchronization.

2.8. POWER TRANSFORMER

Transistor 0601 starts a cycle by allowing current to flow into the primary of T601. As current ramps up with time, the voltage across current sense resistor R608 also ramps to a point where IC601 determines enough power is stored and turns off 0601. As the voltage on 0601 flies upward, power is dumped from the main power transformer through diodes in to the different supplies. D602 clamps ringing which could over-voltage 0601. A sample of this voltage is fed back to the optocoupler to keep the power PET safe encase of a catastrophic failure.

To keep radio frequency radiation to a minimum and reduce transistor heating, a turn-off snubber network is placed across 0601. The transformer has a center leg gap with no gap in the outer legs. This greatly reduces the flux radiating from the cores.

There also may be a large copper strap around T601 to stray flux.

2.9. RECTIFICATION and FILTERS

Currents from the secondary windings are rectified and filtered to create the desired voltages. Low internal series resistance electrolytic capacitors reduce ripple voltage. Small high current capacitors quickly return charging current to the source.

3. HORIZONTAL

The next diagram shows a positive and a negative horizontal section.

This monitor uses the negative approach in the horizontal section.

• +

3.1. PHASE·LOCK LOOP

A phase-locked loop synchronizes the horizontal switch to the timing pulses from the computer. The phase-lock loop compensates for storage delay in 0401.

Incoming horizontal sync is level-translated by 0401 . then fed into the input of the phase comparator.

Transistor 0407 watches the falling edge of the flyback pulse. When. the flyback pulse falls to within a few volts of ground, a rising edge is sent to the other input of the phase-lock loop phase comparator.

The phase comparator operates in an edge lock mode. Integrated circuit IC401( 4046) pin 13 is in a high impedance mode most of the time. If the rising edges fed into pins 3 and 14 of IC401 do not coincide, pin 13 of IC401 goes into a low impedance state for the time difference. Depending on which edge leads the other, current flows into or is pulled out of the filter capacitors C408 and C409.

Voltage controlled oscillator input pin 9 of IC401 determines the frequency and phase of the output square wave on pin 4 of IC401 The free running frequency and lock range is set by C406, R411, R412 and VR401.

diagraml.

If no sync is present the PLL will normally drop to the bottom of the lock range. This causes problems in setting the Horizontal Hold control.

One way of setting the H. Hold VR is to send video into the monitor without H. sync (unplug the green channel and the H. sync cable if any). Adjust H.

Hold for a nearly stable picture. This should insure that the free running frequency is close to the incoming sync frequency.

3.2. MISSING SYNC

When the PLL does not see sync it tries to lower the frequency of the monitor. With some types of composite sync, during vertical sync, where will be no horizontal sync. The PLL will drop the horizontal frequency down a long way during the 3 to 4 missing syncs.

The figure below shows how the input of the voltage controls oscillator (pin 9 of IC401) drops with only one missing sync. Trace A represents the input of the PLL that is watching the flyback pulse. Trace B is horizontal sync with one pulse missing. Trace C comes from pin 1 of the PLL(IC401) and indicates when an error condition arrives. Trace D is the input of the voltage controlled oscillator. Notice how much the voltage drops in one line time and that the recovery is very slow.

12

Trace E shows how the missing sync c.ircuit adds in the missing pulse. The pulse is late by about IuS which is fare better that being one to five line times late. Notice trace G, the input to the VCO, drops very little. The PLL is back on frequency within a few lines. Trace F is pin 1 of the PLL(IC401). The time delay in the missing sync circuit is set by a RC time constant. The voltage in the timing capacitor is seen in trace G.

diagram 2.

If a sync pulse is missing pin 1 of the PLL(IC401) falls. After a time delay set by R415, C410 the missing pulse is added by 0201. The missing pulse circuit is disabled by 0404 if many pulses are missing.

This condition usually arises because the sync is totally gone.

3.3. DOUBLE SYNC

Refer to the sections MISSING SYNC and PLL to understand the phase lock loop and what happens when phase error is detected.

If double sync is sent to the PLL the horizontal frequency will be driven up just like no sync drove the frequency down. A diode(D403) and transistor(0415) is added from pin 4 to pin 14 of the PLL(IC401) to short out any sync pulses that might arrive during the half of the line time when sync

should normally not be. For the half if the line that includes blanking the sync is allowed to pass.

3.4. BASE DRIVE

When turned on, transistor 0410 turns off the horizontal switch 0409. At the same time, current is stored on transformer T40l. When 0410 opens up this stored power supplies turn-on current for 0409.

Resistor R442 sets the average power level to the base drive circuit. Snubbing circuits surround transformer T40l. They control the discharge current waveform into the base.

3.5. BASE DRIVE RESISTOR

The base drive resistor determines the amount of base drive. If the transistor is over driven the V set

looks very good, but the current fall time is poor. If the base current is too small the current fall time is very fast. The problem is that the transistor will have many volts across C-E when closed.

The best condition is found by placing the transistor in the heaviest load condition. Adjust the base resistor for the least power consumption.

diagram 3.

3.6. CHOPPER

The horizontal section does not have a horizontal power supply voltage like most monitors. A chopper is used to take the 150 volt video supply and create the necessary power for the horizontal section. The duty cycle of the chopper is controlled by a pulse width modulator (PWM) IC40l. The PWM watches the current in the horizontal yoke and adjusts the duty cycle to obtain the desired width.

Yoke current can be measured in several different ways. The yoke current is directly related to the voltage across the S capacitor, the average voltage from the chopper and the peak flyback voltage.

The flyback pulse is upside down for the PWM. A capacitor and diode is used to invert the flyback pulse. A resistor divider drops the 1200 volt flyback pulse to 2.5 volts for the PWM.

3.7. HORIZONTAL SWITCH/DAMPER DIODE

On the right hand side of the screen, transistor 0409 conducts current through the deflection yoke.

This current comes from the "S" correction capacitor, C433, which has a charge equal to the supply voltage.

Diode D415 allows current for the left hand side of the screen to flow back through the deflection yoke to C433.

3.8. FLYBACK CAPACITOR

The flyback capacitor connects the hot side of the yoke to B + . This component determines the size and length of the flyback pulse. Choose the flyback capacitor to adjust the second anode voltage.

Capacitors C431 must be precision high voltage high current components.

3.9. "SO CAPACITOR

Capacitor C415 corrects outside versus center linearity in the horizontal scan. The voltage on The S cap has a parabola plus the DC horizontal supply.

Reducing the value of S cap increases this parabola thus reducing the size of the outside characters and increasing the size of the center characters.

3.10. HORIZONTAL LINEARITY

In the yoke current path there is a saturable coil.

Just like a size coil, any inductance in series with the yoke will reduce the size of the picture. This saturable coil will change inductance depending on the amplitude and direction of current flow. At the start of a trace the linearity coil has an inductance of 20 percent of that of the yoke. By the center of the trace, the linearity inductance has decreased to

rest of the trace. Adjust this variable inductor so the right and left sides of the picture are the same size.

3.11. HORIZONTAL DC CENTERING In the horizontal section of a monitor the yoke has DC on the cold end and a flyback pulse on the hot side.

The current ramps in a sawtooth fashion center around zero. If a parallel coil is added the current through the yoke is not effected.

With the addition of a battery and limiting resistor the DC current is added to the current ramp. A plus and minus supply gives full control of the DC offset current.

The batteries or power sources are created off a small secondary winding turning the parallel coil into a transformer. The final circuit has no AC effect on the yoke but can cause a + /- current flow through the yoke.

180uH YOKE

.iffffJiiii-

2 to 20MH COIL

RES. BAT.

~~

-f ~ :cr+

3.12. FLYBACK TRANSFORMER

The flyback transformer is separate from the horizontal section. This is done to allow greater

14

flexibility when changing frequency and tube size. A small independent 'horizontal' section powers the flyback transformer and creates the high voltage.

3.13. X-RAY SHUT DOWN

When a fault in the high voltage section is detected the horizontal base drives are shut down. An over current condition in the high volt supply or an overvoltage condition will trip a TlA31(IC405)1 2N2907(Q413,Q414) latch. Turning off the power resets the latch.

3.14. TUBE BIAS SUPPLIES

Focus and G2 supplies come from a bleeder located in the flyback transformer.

3.15. FOCUS

The focus voltage is obtained form the flyback transformer. There is no focus modulation used in this color monitor.

3.16. MASTER BRIGHTNESS

The G2 voltage comes from the flyback transformer.

3.17. HIGH VOLTAGE REGULATOR

The patented high voltage regulator sits between the supply and the top of the primary of the flyback transformer. An onboard switching regulator is powered from the 17 volt supply. The regulator watches the second anode voltage through a 300-mega Ohm resistor in the flyback transformer. During flyback, the regulator pulls the top of the flyback transformer negative while the flyback pulse is raising the other end. In this way the size of the pulse, as seen by the flyback transformer, is varied to keep the second anode voltage constant independent of load.

The regulator should be adjusted by "high voltage adjustment" to the desired high voltage.

4. VERTICAL DEFLECTION

The TDA 1670(IC301) incorporates all the necessary functions for providing the yoke of a monitor or television receiver with the current required for vertical deflection. Incorporated in silicon is a synchronizable oscillator, ramp generator, voltage regulator, voltage doubler and power amplifier.

4.1. VERTICAL OSCILLATOR

The oscillator is an integrator (pins 4 to 3 of IC301) and a two threshold comparator which switches pin 6 of IC301 high or low to allow the charging of C303.

D301 allows the charge and discharge ramps to have adjustable slopes. Vertical sync pulses come in on pin 5 of IC30l0

The V. Hold VR sets the oscillator frequency.

4.2. RAMP GENERATOR

The ramp generator is made up of a current generator, controlled by current in pin 7 of IC301, and the capacitor from pin 9 of IC301 to ground.

The slope, and thus the size of the linear ramp, is adjustable by setting the current pulled from pin 7 of IC301 This ramp also appears buffered on pin 10 of IC301 at a much lower impedance.

4.3. VERTICAL POWER AMPLIFIER

A power amplifier, with input on pin 12 of IC301, compares the ramp on pin 10 of IC301 to the current ramp through the yoke. R308 and C307 stabilize the high gain power amplifier. Yoke current flows from pin 1 of IC301, through the yoke, the DC blocking capacitor and a current sampling resistor to ground.

Voltage which represents yoke current is then fed back to the input of the amplifier to be compared with the reference ramp

The output stage of the power amplifier is supplied by the 25 volt supply during a trace, and by the vertical flyback generator circuit during a retrace.

The power output stage is thermally protected by sensing the junction temperature and shutting off the current source of the power stage.

The DC bias point is maintained by the divider R310, R311, and R312, Capacitors C309 and C308 fmd the average output voltage. This voltage is then fed back into the input of the buffer amplifier where it is compared to a reference. Any difference in these two voltages causes the DC bias point of the power amplifier to self-adjust.

., .. +

B +

GND

,

...

aND

diagram 4.

4.4. VOLTAGE DOUBLER

In order to obtain sufficiently short flyback times, a voltage greater than that required during scanning must be applied to the yoke.

The flyback generator, during flyback only, supplies (to the power amplifier) a voltage equal to double the supply voltage. Pin 15 of IC301 charges a capacitor up to the supply voltage during a trace and then sets this capacitor on top of the power supply during a retrace, thus doubling the available voltage.

4.5. VERTICAL LINEARITY

Vertical linearity is achieved by feeding a current ramp into the size pin 7 of the TDA1670(IC301). By varying the V. LIN VR the size and direction of the correction ramp can adjusted from positive through zero and to negative.

In the diagram Vi and V2 are two out of phase ramps that are subtracted to achieve a current ramp

diagramS.

which is variable over a range shown by the bottom three traces.

4.6. VERTICAL CENTERING

A current source is connected to the cold side of the vertical yoke. Transistor 0301 can pull DC current from the yoke causing the picture to move up the page. Potentiometer VR30S should be set to center the DATA vertically, not the raster, on the screen.

5. SYNC PROCESSING

To help understand the complex sync processing please refer to both the schematic and the timing diagrams throughout this document.

5.1. COMPOSITE SYNC

Composite sync comes either from the TTL sync input or from composite video through the sync striper 0116. A CMOS 'XOR' exclusive-or gate automatically restores sync polarity if necessary.

See the section on 'POLARITY RESTORATION'.

16

5.2. VERTICAL

Vertical sync is detected by a low pass ftlter and an 'XOR' gate. Vertical sync comes from either the verticallblanking input or the composite sync input.

5.3. HORIZONTAL Horizontal sync processing. See

undergoes several stages of the sections on POLARITY RESTORATION,

CENTERING.

XORINTSC, and DATA

5.4. BACK PORCH

Back porch clamping pulses are created by detecting the trailing edge of sync. The width of this pulse should be a little shorter than the back porch.

Half of the 74LS221 sets the pulse width of the back porch.

5.5. POLARITY RESTORATION

The polarity restoration circuit, an XOR gate, will restore sync polarity if it was fed inverted into the TTL sync input. The RC time constant in the low pass ftlter is about .1 second.

If the input is low with short positive pulses a low pass filter inputs a low to the XOR input B. The output of the XOR gate will be the same as the input. Likewise if the input is high with short low going pulses the low pass ftlter will input a high to the B input of the XOR gate causing it to invert the sync. This way the syncs coming out of the polarity restoration circuit will always have short positive pulses except during vertical.

5.6. HORIZONTAL DURING VERTICAL XOR/NTSC

The H. sync is fed into another exclusive-or gate that looks the same as the first but the time constant is about 200 nano seconds. For normal

the capacitor should be jumpered out.

allow sync to flow through unchanged.

operations This will

In some computers to get vertical sync they simply invert horizontal sync. This very nonstandard process will cause tearing at the top of the page. The phase lock loop in the horizontal section will sense that the sync edge had moved over and will try to compensate.

Normally composite sync looks inverted but actually the horizontal pulse is moved forward so the raising edges are in place. With C188 in place the output of the exclusive or gate will have an 200 nano second pulse on both edges of the horizontal sync pulse.

Sync in

:&

^X-OR

[,vv

input out

I

^o o ^{0 1 0 1}

I

^{1 0 1 1 1 0}

If'

ASl

n rt.

Sync in

B

c.ll n rt.

Sync out

AU

U Lr

Sync in

B

c.ll n _IL

_{Sync out}

I

diagram6

The 74LS22l(IC106) looks at the raIsmg edge of sync. Normally the raising edge is the first edge but during vertical sync it is the second edge. In the case of "inverted H sync" for vertical sync the 74LS22l(ICl06) must look at the first edge all of the time whether the edge is raising or falling. To do this the XOR gate produces a 200 nano second pulse on both edges. The 74LS22l(IC106) will trigger on the first pulse and ignore the second.

5.7. DATA CENTERING

The half of the 74LS22l(ICl06) on the video board is used for data centering. The one shot triggers with

edge of the flyback pulse. The data centering potentiometer should be set to center the picture within the raster.

6. VIDEO 6.1. PREAMP

The LM 120 1 is a wide band video amplifier intended for use in high resolution monitors. The LM120l contains a 100 MHz amplifier, driver, a black level clamp, a background level control and an

a

to 40 dB attenuator circuit for contrast.

A video preamplifier is AC coupled and biased through a resistor from a 2.4 volt reference. The preamplifier drives an attenuator whose gain is controlled by pin 4 (IC1Ol, ICl02, ICI03). The bias level is maintained by comparing the output of the attenuator with the voltage on pin 2 ( ICIOl, ICl02, IC103). In the center of the LM120l is a one transistor amplifier where the gain of each channel is matched to set white level. Another amplifier buffered by an emitter follower, brings the video out on pin 8 (IC10l, IC102, IC103).

6.2. CLAMP

The clamp input pin 9 (IC10l, IC102, IC103) watches the power amplifier's output during the back porch. Any difference in pin 9 and pin 6 (IClOl, IC102, IC103) during clamping will be amplified and used to drive a current source which modifies the voltage on pin 2 (IC10l, IC102, IC103). This clamp voltage will be used to set bias level.

6.3. POWER VIDEO AMPLIFIER

This two transistor cascode amplifier has both emitter and collector peaking to get the best frequency response. The resistor on the base reduces the chance of oscillation and also helps to protect the amplifier from tube arcs. The amplifier is buffered by an PNP/NPN emitter follower. The output of the amplifier is isolated from tube arcing by a carbon composition resistor and an arc arrestor.

6.4. REGULATORS

Four voltages are used to run the video amplifier and sync processing circuit. The 150 volts is used by the back ground to set black level. The 65 volts is used by the video power output amplifier. The 25 volts is reduced to 12 volts by the 7812 regulator for use by the LM12010 The 8 volts lights the filament through a resistor and powers all of the digital logic through a 7805 regulator.

7. TUBE BIASING 7.1. PROTECTION

All elements of the tube have arc protection. The arc current should be returned through the arc ground, not the signal ground, back to the tube in a short direct low impedance path.

7.2. BYPASSING

Grid bypassing is referenced back to the 65 volt supply. Then the 65 volts is bypassed to ground.

This wires all biasing grids in common mode for maximum ripple rejection of the high current 65 volt supply.

7.3. HEATER

The heater is powered from 8 volts dropped by a power resistor.

18

DISASSEMBLY INSTRUCTIONS

As you see the disassembly diagram, you can disassemble the PCB from the chassis as the following procedures.

1. Disassemble cabinet

(1) Remove the 4 screws (

CD )

retaining the rear cabinet ( cover rear ).

(2) Remove the 4 screws (

® )

retaining the front cabinet ( cover front ).

2. Disassemble chassis

(1) Remove the 10 screws (

® )

retaining the chassis top ( shield top ).

(2) Remove the 2 screws (

8) )

retaining the chassis rear ( chassis rear).

(3) Remove the 5 screws (

@ )

retaining the chassis side ( chassis assy ).

(4) Remove the 6 screws (

® )

retaining the chassis side ( chassis assy ).

3. Disassemble PCB

(1) Remove the 2 screws (

(j) )

retaining the main PCB.

(2) Remove the 2 screws (

® )

retaining the power PCB.

(3) Remove the 6 screws (

CD )

retaining the video PCB.

4. Remove the 2 screws (

® )

retaining the chassis PCB ( shield PCB).

The shield PCB will be separated from the chassis bottom ( chassis assy ).

4

PCB POWER PCB

MAIN PCB

RGB VIDEO INPUT 1---1-1--+1

IC101 - IC103 I

HNSYNC SYNCONGREE

H,V,HNSYN

BLOCK DIAGRAM

CONTRAST VR105 BRIGHT VR107

VIDEO IC (LM1201) 0101- 0104

RGB 7 /

.

VIDEO CLAMP

SYNCSEP.

.

0116

C

AMP & BUFFER 0701- 0703

0106- 0109 0111- 0114

SYNCCONV

&HNSYNCSEP IC 107

J I

HNBLANKING UC3709

1

VERTICAL IC

I

^{I V - DY}

VSYNc---~L_

___ IC __

~_l

____

~ ·~.

_ _ C_N_3_0_2 ___

~

HSYNC

TO

HN

BLANKING

DEGAUSS CIR- CUIT L7

NOISE FILTER T601,C601,C602

EMIFILTER

ACINPUT

I

^{H-OSC IC401}

RECTIFIER i---+ D601,C606,C607

I~

.

1 ____

H-DRlVE 0410

HNDRIVE

PROTECT CIRCUIT 0413,414

SYNCHRONIZING 0602, T602

SWITCHING OSC.

IC601

REGULATION IC603,604

--l

~

.

RGB

I

DC CLAMP I I 1 . 0701- 0703

VIDEO CLAMP GEN.

. HSYNC

V SYNC

FROM H-OSC. (IC 401)

H-OUTPUT

~

G1

/

(2

.~

~FOCU S N

~ SCREE

0409

H

^{_____ H-DY} C_N_40_2 _ _ --'

I

HNOUTPUT

~

^FBT

^~SC~5~N

^FOCUS

(G3)

L

HNREGULATION

MODUOLE

DC 150V

SWITCHING SWITCHING DC65V

OUTPUT 0601 ^~ TRANS T603 - - - - + DC25V DC1 DC8V

ADJUSTMENTS ON INSTALLATION

HOW TO ADJUST

Before attempting any of the following adjust- ments, the display should be powered up for a period of 20 minute prior to the adjustment.

1. Switch on the power, and confirm the power indicator (green light). If it does not:

a) Check power source and connections b) Check fuse

c) Call a service engineer.

2. Turn the contrast and brightness controls clock- wise fully.

3. If no picture appears, a) Check the sync signal

* H/V separate sync mode

: sync signal input

* H/V composite sync mode

: sync signal input

* Composite sync on green mode

: green sync signal input Three type of sync mode, HN separate sync mode, H/V composite sync mode and com- posite sync on green mode are automatically selectable. The priority is HN composite sync.

b) Check the 75 ohm termination switch.

This unit included beam current limit circuit.

If limit circuit is operated, no picture appears.

After checking termination switch, switch on the power again.

4. When a picture appears, notice the stability of the picture. If it is not stable or it is not dis- played at the center, swicth off the mains supp- ly and remove the lid for adjustment at back cover by removing only one screws (refer to Fig. 2).

5. Power on and adjust controls with plastic driver. Note that it is important to use a plas- tic driver. Otherwise the adjustment could result in a short circuit and breakdown of dispa- ly.

6. To display appropriate picture on screen, ad- just the control with plastic driver, refer to Fig.

3. and Table 1.

7. If you want to readjust another controls - Focus, Screen, H-center, H-linearity, R.G.B-drive, R.B-bias, NTSC/XOR Selector - remove the back cover by removing only four screws.(refer to Fig. 4, 5, 6, 7, and Table 2 ).

8. In the case of horizontal stripes at top posi- tion, change the NTSC/XOR selector switch.

9. If there is any problem or trouble in the read- justment above, contact the supplier of the equipment.

Finally, power off and replace covers as it was Turn brightness and contrast controls to their nor- mal operating position of yours.

g.2.

Fig. 3

Screw Lid for

adjustme nt

4) 0

1\ j - - /

p I~

~

.

§

~~~~~~~~~~.i

^.~

~ I~

~ ^I~

~

I~

~m~~~~

@I/

\ 0

r - - l .----n

=~18

^@

~~~@@I\

^L...,

V -linearity

V-size --~

V-hold V-center

H-hold

Side Pin _ _ ~

H-width - - - +

24

G-DRIVE

©

SUB CONT

fi

Sub- Contrast

PIN \81

H- PHASE

H-WIDTH

©

^H-phase

Adjustment shown below is required when signals other than the recommended signal are received.

Condition Picture too wide.

Position to be adjusted Adjust H width VR402

Picture shortened verti- Adjust V size

ally. VR301

Picture deviated to the ight

Picture deviated upwar

Picture has horizontal tripes.

Adjust H phase R106

(Adjust H cen- er position

R403)

Adjust V center VR305

Adjust H hold VR401

Condition Picture too narrow.

Picture stretched verti- ally.

Picture deviated to the eft

Picture deviated ownward

Picture rolls vertically

( Table. 1)

Position to be adjusted Adjust H width VR402

Adjust V size VR301

Adjust H phase R106

(Adjust H cen- er position

R403)

center VR305

Adjust V hold VR303

Condition Vertical lines are not traighten.

• ~

Horizontal lines are ot display with equal

pa~i~ll!

Position to be adjusted Adjust Side Pin VR304

Adjust V inearity.

VR302

Condition Vertical lines are not traighten.

Horizontal lines are ot display with equal Pac • . :.:.:.;.;.:.;.;.:.:.:.;.;.;. .

•••••

•• 1 ••••.•• • •.• • •• · .•• · •••. ·:· ••. ·.1:

Position to be adjusted Adjust Side Pin.

VR304

Adjust V inearity.

VR302

(Continued Table. 1 )

Condition Position to be adjusted Vertical lines are not Adjust H

~isplay with equal space. inearity.

•

: ••••...•.••. .;;.; L403 :;-:" .. <:: .: ... :::::

< ...•.•••••..••••

Vertical lines are not

~traighten at top posi- iOO • •

Adjust H hold VR401

Condition Position to be adjusted Vertical lines are not Adjust H display with equal space. lineraity .

Picture has horizontal

!itripes at top position.

•

L403

Check NTSC/XOR switch .

SW106

( Table. 2 )

26

Screw Screw

Screw Fig. 4.

B-bias -bias

F.=~==F==¥-===iI.

Fig. 6.

V-linea V-size

n

----

V-hold V-cent H-hold SidePin H-widt

er

f1.

G-drive R-drive B-drive

°1\ _II II / /0

"~

⁷

jOo

I---~

.Qfu. ⁰

-

^{0 0}

-

_0" '0 ^{0 0}

t/'~

..

~lL-r

⁰

" / 0

.

}f 1

^{.----. \ 0}

Sub-co ntrast I = !J1 t::!J ^@ ~~~ ^~@T _~ H-phase NTSC/XOR selector

Fig. 5

Focus

-linearity

Fig. 7.

ALIGNMENT

Note : This adjustment requires the connection of a personal computer to the Monitor. Although the Monitor is adjusted before it is delivered, readjust- ment may be required when the setting postion is changed or when a component is replaced.

1. B

+

Adjustment (1) Operate the monitor.

(2) Connect the plus pole of DVM(Digital Multi Meter) to the GT pin with B

+

marking and connect the other pole(GND) to chassis GND.

(3) Rotate the B + voltage adjusting control(VR601) to provide a DC150V.

2. Horizontal Frequency Adjustment

(Illstrnment ill use,' frequency counter,scope probe) (1) Connect the plus pole of the scope probe to

RED wire of DY and the minus pole to chassis frame.

(2) At self raster, adjust the horizontal frequency con- trol(VR401) so that the horizontal frequency IS

62.7KHz.

(Free running frequency: 62.7KHz ± 500Hz) 3. Horizontal Phase Adjustment

Adjust VR106(horizontal phase control) so that the image( or test pattern) is placed on the center of the raster.

4. Vertical Frequency Adjustment

(Instnl1llent ill use,' frequency counter,scope probe) (1) Connect the GND pole. of the scope probe to

chassis frame and the scope probe to DY pin connected to yellow wire.

(2) At self raster, adjust VR303 so that the vertical frequency is 54Hz.

(Free running frequency: 54 ± 2Hz) S. Focus Adjustment

(1) Operate to display the full white pattern on the screen.

28

INSTRUCTIONS

(2) Adjust the contrast control so that the brightness is 15FIL.

(3) Change the pattern into alphabetical characters on the screen.

(4) Rotate the focus adjusting control in FBT for the best focus.

6. Side Pincushion Adjustment

Adjust the side pincushion control(VR304) until the side line becomes straight.

7. Horizontal Linearity Adjustment

Adjust the horizontal linearity control(L403) until the horizontal linearity is best.

8. Vertical Linearity Adjustment

Adjust the vertical linearity control(VR302) until the vertical linearity is best.

9. Horizontal Centering Adjustment

Adjust VR403 until the horizontal center is set at screen center. (Horizontal centering tolerance is

± 3 mm)

10. Vertical Centering Adjustment

Adjust VR406 until the vertical center is set at screen center. (Vertical centering tolerance is ± 2 mm) 11. Width Adjustment

Adjust the horizontal width control(VR402) so that the horizontal width of displayed pattern is 360 mm.(Tolerance is ± 5 mm)

12. Vertical Size Adjustment

Adjust the vertical size control(VR301) so that the vertical size of displayed pattern is 270mm.

(Tolerance is ± 5 mm)

13. Color Purity Adjustment

The display monitor must have been operating 20 minutes prior to this procedure, and with the faceplate of the CRT at room temperature. The dis- paly monitor is equipped with an automatic and manual degaussing circuit. However, if the CRT shadow mask has become excessively magnetized, it may be necessary to degauss it with a manual.

(1) Check for the correct location of all neck com- ponents. Refer to Figure 9.

(2) Rough in the static convergence at the center of the CRT, as explained in the static convergence procedure.

(3) Rotate the contrast control to the center of its range and rotate the brightness control to its maximum clockwise position.

(4) To obtain a blank raster. Rotate the screen con- trol(part of F.B.T) clockwise until a normal raster is obtained.

(5) Rotate the red bias(VR 701) and blue bias (VR702) controls to the maximum counterclock- wise positions.Rotate the screen control VR suf- ficiently in a clockwise direction to produce a green raster.

(6) Loosen the deflection yoke clamp screw and pull the deflection yoke as close as possible to the purity and convergence magnets assembly.

(7) Begin the following adjustment with the tabs on the round purity magnet rings set together. Ini- tially, move the tabs on the round purity magnet rings to the side of the CRT neck. Then, slowly separate the two tabs while at the same time rotating them to adjust for a uniform green ver- tical band at the center of the CRT screen. Refer to the Figure 8.

(8) Carefully slide the deflection yoke forward to achieve green purity (uniform green screen).

Note : Center purity is obtained by adjusting the tabs on the round purity magnet rings. Outer edge purity is obtained by sliding the deflection yoke forward. tighten the deflection yoke clamp screw.

(9) Check for red and blue field purity by reducing the output of the screen control and alternately

blue(VR702) bias controls, and touch up the ad- justment, if required.

(10) Perform the "White balance Adjustment" proce- dures.

14. Screen Adjustment

Operate the computer to display the full white pat- tern on screen.

Adjust screen VR(in FBT) so that back raster ap- pears at brightness and contrast VR max, but disap- pears at brightness VR center( detent position) and contrast VR max.

Green Raster Fig 8. Color Purity Adjustment

Deflection Yoke Clamp screw

conv. magnets

~ixZole, conv. magnets

t.l

^{~ Purity magnet~}

Deflection Yoke tilt adjustment wedge Fig 9. Picture tube neck components location

15. White Balance Adjustment (instrument In Use :

(1) Operate the computer to display the full white pattern on screen. (Refer to Timing Chart) (2) Turn the screen control fully clockwise. Turn the

red and blue bias control counterclockwise. Set the brightness control and the red, green and blue drive controls at the center positions.

(3) Rotate the screen control counterclockwise until a raster (either the red, green or blue) appears dimply on the screen.

(4) Rotate two bias controls counterclockwise until the raster becomes somewhat white: position rotated controls must be the ones which control the colors other than the raster's colors.

Note :

Adjust VR 701 if red appears.

Adjust VR702 if blue appears.

Adjust screen control if green appears.

(5) Rotate the red, green and blue drive (VR101, VR102, VR103) controls until the raster is white.

(6) Set the brightness control at its maximum posi- tion and adjust the Sub-Contrast control until a reading of ^{26 ±} 1 F/L appears.

(7) Turn the brightness control in either direction to check that the picture maintains a good white balance.

(8) Repeat steps 3 thru 7 for readjustment.

16. Static(center) Convergence

Switch the monitor ON and warm up for 15 minutes.

Operate the computer in such a way that the cross hatch pattern is displayed on screen. (Fig 10.) Convergence error should not be over 0.5 mm in corner, O.3mm in center

Proceed as follows.

(1) Locate the pair of four pole magnet rings.

(2) Rotate the individual rings (change spacing be- tween tabs) to converge the vertical red and blue lines.

(3) Rotate the pair of rings (maintaining spacing be- tween tabs) to converge the horizontal red and blue lines. (Refer to Fig. 11.)

30

(4) After completing the red and blue center con- vergence, locate the pair of six pole magnet ring.

(5) Rotate the individual rings (change spacing be- tween tabs) to converge the vertical red and blue (magenta) and green lines.

(6) Rotate the pair of rings (maintaining spacing be- tween tabs) to converge the horizontal red and blue (magenta) and green lines. Refer to figure 12.

Horizontal:

16 Lines Min.

Vertical:

12 Lines Min.

Fig. 10. Crosshatch Pattern

I

^-...,

BLUE~ I .. _~

> - - - -

t- ^---

I

I

~ ^t

I I

RED

I

Fig. 11. Static Convergence A

I

BLUE/~

I ..

RED ^I

,

- - - - t- - - - -

I

I I lG&E!N

I

Fig. 12. Static Convergence B

17. Dynamic Convergence

Dynamic convergence (convergence of the three color fields at the edge of the CRT screen) is accomplished by the proper insertion and positioning of the three wedges between the edge of deflection yoke and the funnel of the CRT.

This is accomplished in the following manner:

(1) Switch the display monitor ON and allow it to warm up for 20 minute.

(2) Apply the crosshatch pattern (Fig. 10) from the computer to the display monitor. Observe spacing between lines around the edges of the CRT.

(3) Tilt the deflection yoke up and down. Insert tilt adjustment wedges 1 and 2 between the deflec- tion yoke and the CRT until the misconvergence ilIustrasted in Figure 13 has been corrected.

(4) Tilt the deflection yoke right and left. Insert tilt adjustment wedge 3 between the deflection yoke and the CRT until the misconvergence illustrated in Figure 14 has been corrected.

(5) Alternately change the spacing between, and depth of insertion of, the three wedges until proper dynamic convergence is obtained.

(6) Check purity and readjust, if necessary.

I

BLUE (RED)

GREEN

J ... RED

t--

(BLUE)

I

BLUE (RED)

---- ---

-~[---4_

, I'

GREEt

I \

R D (BLUE)

-..1

^'411'

Fig. 13. Dynamic Cinvergence A

GREEN

gg. 14. Dynamic Convergence

WEDGE 1

2

BLUE (RED)

Fig. 15. Deflection Yoke Rear View

YOKE

TROUBLE SHOOTING GUIDE

NO POWER

DOES 150V APPEAR BETWEEN THE GT602 AND GROUND

I

1 1

I

YES

I

C?

1

DOES 300V OVER APPEAR BETWEEN 1. DISCONNECT CN 601 PIN#1 AND #4 OF D601 ?

I

2. RECHECK 150V APPEAR BETWEEN GROUND

THE GE601 AND

I

YES

I

F601, SWl,2 D601 NTH601,602

Circuits Checked:

*

Power Regulator Circuit

*

Protector Circuit

*

Horizontal Sync Circuit

~

1

IC601,603 0601,602

1

I

NO

I

1

1. DISCONNECT CN603 2. RECHECK 150V APPEAR

BETWEEN THE GT601 AND GROUND

VIDEO BOARD 0101,102,103,104 0106-109,0111-114

NO LED LIGHT UP

DOES 16V APPEAR BETWEEN THE R631 AND GROUND ?

CHECK NO POWER

32

I

YES

I

1

LED DIODE

DEFBOARD IC301,401

0409,411 D415,420

NO RASTER APPEARS I

. Circuits checked : 1. No raster appears.

* Power circuit

* H-sync circuit DOES 150V APPEAR AT GT601 ?

*

Protector circuit

I

I

YES

I

DOES 11.6Vp.p WA VEFORM APPEAR AT IC401 #4 ?

YES

I

^NO

.

DOES 12V APPEAR AT 0413 COLLECTOR?

YES

I

NO

I

DOES 800Vp.pWAVEFORM APPEAR AT 0411 EMITTER?

I

I

YES

I [3

DOES 1000Vp.p WAVEFORM APPEAR AT 0409 EMITTER --

~----'I 1

1

T

2. A high voltage develops but no raster appears.

* Video output circuit 3. A high vol~age is not

developed.

* High voltage circuit CHECK POWER CIRCUIT

CHECK 0410,412,0602

CHECK 0413,414, IC405, D435

CHECK 0411,501, D420

CHECK 0409,406, D415

relaJed circuits.

1

Circuits Checked:

*

Video Circuit And Its

NO PICTURE APPEARS I

DOES INPUT SIGNAL WAVEFORM APPEAR AT BOTH ENDS OF RI0l, R121, R141 ?

1

I

YES

DOES 5Vp_p WAVEFORM CHECKTHEST AND INPUT CIRCUIT

T

ED CIRCUIT APPEAR AT ICI09 #12

I YES

I

DOES 35Vp_p WAVEFORM APPEAR AT CNI06,107,108 ?

YES

I

I

^NO

I I

VIDEO CLAMP CIRCUIT

I

L 1

^0701-0703

I

NO

I

SYNC PROCESSOR

1

I

IC106, 107, 109

L

^{VIDEO AMP}

1

.. I

0101· 0104 0106·0109 0111· 0114

I

AND ITS RELAT

0801·0802, 0811· 0812, 0821-0822 ANDCHECKTH

BETWEEN THE

E CONNECTIONS MONITOR&PC

Note: If the picture does not appear, fully rotate the brightness contrast control clockwise before inspecting.

34